Aqueous polymer dispersions preparation

Abstract

A process for the preparation of aqueous polymer dispersions comprising polymerizing compounds with unsaturated ethylenic bonds at a temperature of 10° to 100° C. in the presence of an at least partially water-soluble free-radical initiator and at least one starch and/or starch derivative and optionally present conventional adjuvants with the starting mixture containing not more than one third of the total monomers and the remaining monomer being added during the polymerization, the initiators being at least one member of the group consisting of hydrogen peroxide, ketone peroxides and organic hydroperoxides in an amount of at least 30 mmol per kg of total monomer mixture and optionally present water-soluble reducing agents and the starch is water-soluble or gells in water and contains not more than 30% by weight of amylose and the starch derivative is hydrolyzed starch in an amount of at least 0.6% by weight based on the total monomer weight.

What we claim is: 
     
       1. A process for the preparation of aqueous polymer dispersions comprising polymerizing compounds with unsaturated ethylenic bonds at a temperature of 10° to 100° C. in the presence of an at least partially water-soluble free-radical initiator and at least one starch and or starch derivative and optionally present conventional adjuvants with the starting mixture containing not more than one third of the total nomomers and the remaining monomers being added during the polymerization, the initiators being at least one member of the group consisting of hydrogen peroxide, ketone peroxides and organic hydroperoxides in an amount of at least 30 mmol per kg of total monomer mixture and optionally present water-soluble reducing agents and the starch is water-soluble or gells in water and contains not more than 30% weight of amylose and the starch derivative is hydrolyzed starch in an amount of at least 0.6% by weight based on the total monomer weight. 
     
     
       2. The process of claim 1 wherein the peroxide initiator is used in combination with a member selected from the group consisting of ascorbic acid and reducing sulfur compounds. 
     
     
       3. The process of claim 1 wherein the initiator is at least one member of the group consisting of alkyl hydroperoxides and aralkyl hydroperoxides. 
     
     
       4. The process of claim 3 wherein the peroxide initiator is used in combination with a member selected from the group consisting of ascorbic acid and reducing sulfur compounds. 
     
     
       5. The process of claim 1 wherein the peroxide initiator is present in the starting monomer and polymerization is controlled by addition of reducing agent. 
     
     
       6. The process of claim 1 wherein the amount of starch or starch derivative is at least 0.5% by weight of the monomer mixture before polymerization. 
     
     
       7. The process of claim 1 wherein the amount of initiator is at least 45 mmol per kg of total monomer. 
     
     
       8. The process of claim 1 using 15 to 95 mol % of reducing agent based on the initiator. 
     
     
       9. An aqueous polymer dispersion produced by the process of claim 1.